Flashcards in Connective Tissue Deck (18):
What are the 4 basic types of tissue?
What are the types of CT?
6. Haemopoietic (bone marrow and lymphoid)
What cells does CT arise from?
Mesenchymal stem cells
Suggest 6 functions of CT?
1. Connects cells to form tissues, tissues to form organs and organs to form the body. Some CT provides support (cartilage/bone).
2. Transport: medium for diffusion of nutrients and wastes.
3. Protection: cushion between tissues and organs, and insulation (adipose).
4. Storage (adipose).
5. Defence against infection (blood/lymph/fixed and wandering cells)
6. Wound healing (macrophages, fibroblasts, myofibroblasts).
What are the 3 general components of CT proper?
3. Ground substance
Which cells secrete the fibres (collagen) and ground substance of CT?
As well as producing CT, what is an important role of fibroblasts?
- Wound healing
- Scar tissue formation - myofibroblasts = modified fibroblasts containing actin. Responsible for wound contraction when tissue loss has occurred.
What are the 3 types of fibres in CT and why are these important?
1. Collagen - flexible with high tensile strength
2. Reticular - provide a supporting framework
3. Elastin - allows tissue to recoil after stretch
What is the most common protein in our body?
- 1/4-1/3 of whole-body protein content
How many types of collagen do we have and which is the most common?
- Type I (90% of all collagen)
What is the difference between type I, II, III & IV collagen?
- Type I: fibrils (composed of alpha chain triple helix) aggregate into fibres and fibre bundles (e.g. tendons, organ capsules and skin dermis).
- Type II: fibrils do not form fibres (e.g. hyaline and elastic cartilage).
- Type III: fibrils form fibrils around muscle and nerve cells and within lymphatic tissues and organs - reticulin.
- Type IV: unique form present in basal lamina of basement membranes.
What are reticular fibres and where are they primarily found?
- Consist of type III collagen.
- Form an irregular anastomosing network throughout lymph nodes, with lymphocytes densely packed in the spaces between the fibres.
What are elastic fibres composed of?
- Primary component = elastin.
- Enfolds and is surrounded by fibrillin microfibrils.
Where are elastin fibres found?
- Occur in most CT but to widely varying degrees.
- Important role in:
~ artery walls (allows stretch and recoil)
~ elastic cartilage
Which disease is associated with abnormal elastic fibres?
- Marfan's syndrome
- Autosomal dominant - abnormal expression of fibrillin gene
- Abnormally tall, arachnodactyly, frequent joint dislocation, risk of aortic rupture.
What is the ground substance of CT made up of?
- Proteoglycans = large macromolecules consisting of a core protein to which glycosaminoglycans (GAGs) are bound.
- High water content - viscous.
Why does ground substance have a high water content?
GAGs attract water as they are:
- strongly hydrophilic
- highly negatively charged - attract cations (e.g. sodium ions), causing water to be sucked into the matrix